About the Java Technology

( http://docs.oracle.com/javase/tutorial/getStarted/intro/definition.html )




.java : plain text files
.class : bytecodes ( the machine language of the Java Virtual Machine )

.class files are capable of running on many different operating systems.



The Java platform has two components.

One is the Java Virtual Machine and the other is Java Application Programming Interface (API)


The Java platform can be a bit slower than native code.
But, Java has great portability.

JVM means a Virtual Machine for the Java platform.